Generally, a battery charger is an electronic assembly comprising electrical, mechanical, and/or electronic components that together perform multiple functions associated with delivering electrical energy to a battery.
Battery charging is carried out in existing devices in several different ways, including linear dissipative voltage regulators, various types of thyristor regulators, and various types of switchmode regulators. Many existing (commercial) battery chargers are transformer type thyristor-controlled battery chargers that are larger and heavier than switchmode type battery chargers. Existing battery chargers including switchmode type battery chargers usually have a poor power factor (i.e. ratio of real power flowing to the load, to apparent power in the circuit), and therefore draw more input current than is necessary, and have non-sinusoidal AC input current.
Existing battery chargers may provide: reverse polarity protection; jumper selectable output voltage (e.g. twelve-volt or twenty-four volt charging); automatic charge cycles; temperature compensation; electromagnetic interference (EMI) filtering; surge protection (protection from unwanted transient electrical energy coming from the AC power source attached to the battery charger); alarm relays; fuses for overcurrent protection on the AC input and the DC output; power factor correction; configuration of the charger via a digital interface; battery charging algorithms; electromagnetic emission control and immunity; alarm systems with low power consumption latching relays; and/or, LCD battery charger status display. However, many existing battery chargers have no reverse polarity protection, no thermal protection, no alarm relays, no text display, no digital communications interface, no microprocessor, no capability to select twelve volt and twenty-four volt operation in the same charger, no capability to charge a zero Volt battery, etc.
Some existing battery chargers use mechanical adjustment devices such as potentiometers, DIP switches, pushbuttons, slide switches or other adjustment mechanisms that have a high risk of failure, intermittent functionality, or wear.
Some existing devices' “housekeeping power supplies,” which power on-board control circuitry, are only supplied from AC line power and therefore cannot function if a battery is not connected. Some existing battery chargers may mistake a “zero volt battery” (a battery which has never been charged or which has been deeply discharged and therefore has very low voltage across its battery terminals) for a short circuit and therefore will not initiate battery charging, and/or may be unable to operate due to lack of housekeeping power from the zero volt battery.